While Williams' singularly frenetic brand of humor helped him make a name for himself first on the stand-up stage and, later, on such television series as the "Happy Days" spinoff "Mork and Mindy," it was on the big screen where he showed America another side of himself - and proved that he wasn't just a comic, but that he was an actor.

As his fans come to terms with his far-too-early passing, we remember five of his most memorable movie roles.

5. "Aladdin"(1992). If there was a role on this list that feels like it was custom-made for Williams' motormouthed energy, it was his largely ad-libbed turn as the big, blue genie in this Disney classic. It was animated, so we never saw his face, but he left an indelible impression in co-director John Musker and Ron Clements' film. As the story goes, he agreed to do the role for scale, but only on the condition that his name not be used in connection with the film's marketing and that his character's image not take up more than 25 percent of ads. But when they saw the finished product, Disney brass knew what they had on their hands and reportedly went back on the deal, causing a falling out with the actor. It was only temporary, though. He would return to voice the genie in the 1996 direct-to-DVD sequel "Aladdin and the King of Thieves." He would also be paid a whole lot more than scale for his trouble.

4. "Dead Poets Society" (1989). For movie fans of a certain age, Williams' turn in this Peter Weir-directed drama was a formative one. In it, he played the decidedly nontraditional English teacher who inspires a class full of boys at a stuffy, tradition-bound Eastern prep school -- and, for many moviegoers, he became the breath of fresh academic air that they could only wish for in real life. Yes, we have all been taught what the Latin phrase "carpe diem" means, but it was Williams that unforgettably demonstrated in this role what it really meant. His character's name was Mr. Keating, but he insisted his students call him by another title, and it's one that - for those who learned from his performance -- might as well be carved on Williams' gravestone: "O Captain! My Captain!"

3. "Good Morning Vietnam"(1987). There were two distinct sides to Williams' talent. On the one hand, he had an uncanny ability to show restraint on-screen when a role required that, while other roles saw him taking full advantage of his cyclonic comedy tendencies. In this Barry Levinson-directed dramatic comedy, however, he was able to combine the two in a single role, portraying real-life Armed Forces Radio broadcaster Adrian Cronauer, who was known for his larger-than-life on-air personality during the Vietnam War. The role required real dramatic chops for much of the film, but Williams famously ad-libbed many of his "on-air" scenes, tapping into the wit and style he had honed years earlier on the stand-up stage. The result is pure Williams -- and pure entertainment. It would also earn him the first of his four career Oscar nominations.

2. "Good Will Hunting" (1997). It was Williams' turn in this Gus Van Sant-directed drama that brought him his Oscar, for best supporting actor, playing a big-hearted therapist to Matt Damon's title character. Like "Dead Poets Society," it was one of those rare roles for which he suppressed entirely that manic energy for which he had become known. While that robbed him of his safety net -- that is, a natural-born ability to make people laugh -- it shined a spotlight squarely on his acting skills. The result was a moving and memorable performance that the Academy of Motion Picture Arts and Sciences couldn't help but to honor. He would receive three more Oscar nods in his career - for 1987's "Good Morning, Vietnam," 1989's "Dead Poets Society" and 1991's "The Fisher King" - but this would be the only role that brought him the gold. (This film is rated R. The video clip below contains profanity.)

1. "Mrs. Doubtfire." Once more blending drama and comedy, Williams donned an old-lady getup for the role that might be the one for which he is most remembered. Directed by Chris Columbus, it saw Williams play an actor who goes undercover as a nanny - complete with Scottish accent - in order to be closer to his estranged kids, who, like his wife, don't recognize him. Silly premise? Yes. But a sweet film and a whole lot of fun, too. That translated into a major box office success, as "Mrs. Doubtfire" finished second in grosses only to "Jurassic Park" in 1994. Talks of a sequel have been discussed for years -- at least since 2001 -- and they picked up steam this spring, with Columbus and Williams set to return, and with a screenwriter being hired. Those plans are in doubt at best, as it would be ridiculous for anyone to think they could fill Williams' sizable shoes.